Combustion engine systems include engines having combustion chambers in which air and fuel is combusted for conversion into mechanical rotational power. Combustion engine systems also include breathing systems including induction systems upstream of the engine for conveying induction gases to the combustion chambers, and exhaust systems downstream of the engine for carrying exhaust gases away from the combustion chambers. The breathing systems may also include exhaust gas recirculation (EGR) passages and valves to recirculate exhaust gases out of the exhaust system and back to the engine via the induction system for lower NOx emissions.
Combustion engine systems also may be equipped with turbochargers to pressurize the induction gases before entry into the combustion chambers to efficiently increase engine power. A turbocharger basically includes a compressor in the induction system for generating induction boost pressure, a turbine rotatably connected to the compressor and disposed in the exhaust system and powered by pressurized exhaust gases for driving the compressor. Pressurized exhaust gases from the engine impinge on a bladed rotor of the turbine to pneumatically spin the rotor. The spinning rotor and a shaft mechanically spin a bladed impeller of the compressor. The spinning impeller pressurizes induction gases to increase the mass of induction gases supplied to the engine, thereby allowing more fuel to be burned for increased combustion so as to increase engine power output for a given engine displacement and speed.